That's not confirmed, but yeah, most probably true.
I hung out with my cousin yesterday, the one who works for Google. He moved from working on core apps and is now a part of the Android @ Home team. Couldn't tell me much about anything that's unannounced, but I could tell from his reactions when I asked him about certain things what's a priority and what isn't. There's going to be some cool shit unveiled at IO for sure including the new tablet.
Also, as it turns out, the Android @ Home team is actually a very large team for an Android subset. We haven't heard anything about it for a while but it's defo a priority for them.
Also, ICS might not be running on a great percentage of devices yet, but remember that it was unveiled last October. So it has already been 9 months since it was announced. And IO is still another month away, and it likely won't roll out to any devices for at least another month. By the time it actually starts hitting devices it will have been almost a year since ICS was announced. There's been far shorter gaps between releases before.
As far as it taking a long time to roll out ICS, what you have to remember is that 2.3 to 4.0 requires a lot of resources from the OEMs and carriers. It's not a minor update. So yeah adoption is slow, but I think adoption from ICS to Jelly Bean will happen much faster.